Pacific Oysters

Shellfish, Pacific Northwest

Pacific Oysters, Photo By Bud Logan

Pacific Oysters change sex at some point during their life, usually spawning first as a male and subsequently as a female. Environmental conditions may affect the sex. When food supplies are plentiful, males tend to change into females, and vice versa when food supplies are in poor supply.

Pacific oysters usually produce between 50 to 100 million eggs which they release over several spawning bursts. The female discharges her eggs up to 30 cm from its body in the form of white clouds. The male oyster adds its sperm.

The Pacific Oyster can live and grow in water temperatures between 2 to 20°c, but has higher growth rates in water temperatures of 12 to 15°c. Spawning is temperature dependent and occurs in the summer months when water temperatures are typically warmer.

The overall growth varies by tidal height, season and the area in which they grow. The Pacific Oyster prefers to attach itself to a hard surface and can be found on firm mud, sand, gravel or a rock substrate in the lower inter tidal zone, down to a depth of roughly 4.2 meters.